1. Field of the Invention
The present invention relates generally to fastening devices and, more particularly, to threaded plugs for attachment to trench plates for accommodating swivel hoist rings therein.
2. Description of Related Art
Steel trench plates are used to cover trenches in streets and roadways in order to facilitate traffic flow during construction or repair. In order to lift a steel trench plate, one or more fastening devices, such as hoist rings, are typically secured to the steel trench plate. Prior art fastening devices have included threaded rods formed into a loop and permanently affixed to the steel trench plate. Swivel hoist rings have also been used as fastening devices for steel trench plates. A typical swivel hoist ring, such as disclosed in U.S. Pat. No. 3,297,293 to Andrews et al., may comprise an eye member which is pivotally and rotationally mounted onto a base.